Bulked non-wovens



Aug. 23, 1966 w. T. ALLMAN, JR.. ETAL 3,268,084

BULKED NON-WOVENS Original Filed DSC. 4, 1958 United States Patent O 3,268,084 BULKED NON-WQVENS William T. Allman, Jr., Charles W. Joseph, and Ralph G.

Higgins, Jr., Rock Hill, S.C., assignors to Celanese Corporation of America, New York, NX., a corporation of Delaware Original application Dec. 4, 1958, Ser. No. 778,248, now Patent No. 3,100,328, dated Aug. 13, 1963. Divided and this application Feb. 20, 1963, Ser. No. 266,123 The portion of the term of the patent subsequent to Aug. 13, 1980, has been dlsclaimed 2 Claims. (Cl. 210-503) The instant application is a divisional application of application Serial No. 778,248 now Patent No. 3,100,328.

The present invention relates to novel non-woven articles characterized by high bulk and a soft hand.

It is an object of the invention to provide non-woven filamentary materials of increased covering power, resilience, insulation and strength as well as of softer hand.

Other objects and advantages of the invention Wil-l become apparent from the following detailed decription and claims.

In accordance with one aspect of the present invention, a non-woven article comprising organic acid ester of cellulose filaments bonded to one another at spaced locations is subjected to steaming whereby the physical properties of the article are changed, viz. the covering power is increased along with the resilience, insulation and strength while the density is decreased and the hand is improved.

The steaming is advantageously carried out at a temperature ranging from about 95 to 180 C. and preferably 110 to 125 C. The pressure is generally superatmospheric but atmospheric or even reduced pressure may prevail.

The duration of the steam treatment will depend upon the temperature and upon the thickness and construction of the article being treated. Generally it will be at least about l min-ute to produce a substantial improvement rand it may be as long as l minutes or more. At the preferred temperatures the duration of steaming is preferably about l to 5 minutes.

The non-woven article may comprise a web, fleece or sheet material composed of staple length fibers either randomly disposed or oriented to a greater or lesser degree as by carding, the fibers being bonded to one another at spaced points.

In accordance with another aspect of the invention, the non-woven article comprises a web, fleece or sheet material composed of substantially randomly directed substantially continuous filaments bonded to one another at spaced points of contact. Advantageously such webs may be formed as described in detail in copending application Serial No. 744,844 filed June 26, 1958. Briefly, filament-forming material in liquid phase is extruded through a plurality of orifices to form continuous filaments which may be agitated, such as by blasting With air, while still mutually adhesive, to cause them to swirl about and coalesce randomly. The filaments are continuously drawn away from the extrusion location in the form of a nonwoven web or fleece. The web so produced can be directlysteamed or it may be subjected to intermediate treatments such 'as hot calendering to increase the number of points of fusion and the density. Various adsorbents, pigments, etc. can be incorporated in the non-woven either by being added to the dope which is being spun or by being deposited on the web as formed.

The denier of the individual filaments of the nonwoven may vary within wide limits, eg. from less than 1 up to 20 or more, although preferably it ranges from about 2 to 16. The weight per square yard of the nont 3,268,084 ce Patented August 23, i966 woven can also vary widely, depending upon its thickness, density, etc.

The filamentary material may comprise an organic acid ester of cellulose such as cellulose acetate, cellulose propi-onate, cellulose butyrate, cellulose actate propionate, cellulose acetate butyrate, or the like. The esters may be triesters, i.e. esters containing fewer than about 0.29 free hydroxyl groups per anhydroglucose unit of the cellulose molecule, or they may be conventional secondary or ripened esters containing about 0.6 free hydroxyl groups per anhydroglucose unit. The non-woven articles may comprise mixtures of these filamentary materials with each other or with other filamentary materials either natural or synthetic, e.g. cotton, wool, silk, rayon, nylon, polyethylene terephthalate, acrylics, polyolefins, polymers of halo-olefins such as vinyl chloride or vinylidene chloride, etc.

In accordance with another aspect of the invention, the non-woven article may comprise a mixture of continuous filaments of a cellulose triester and of a secondary cellulose ester, e.g. cellulose triacetate and conventional cellulose acetate. This can be formed by simultaneously extruding a solution of cellulose triacetate in methylene chloride through one set of orifices and extruding a solution of conventional cellulose acetate through a second set of orces. The filaments formed by such extrusions are positioned near each other and a blast of air causes them all to swirl and entangle with one another, becoming fused at spaced points. Steaming produces exceptionally high bulk because of the effect on the filaments individually as Well as because of the differences in the thermal characteristics of the different types -of filaments.

While not wishing to be bound thereby, the change in physical properties upon steaming is believed due to the following effects: Upon drying of freshly formed cellulose ester filaments, especially of substantially continuous filament non-wovens wherein the filaments are fused at spaced points of contact, the filaments undergo compression or other stresses between fusion or weld points. During the subsequent steaming the stresses are released and the filaments become distorted into sinusoidal, helical or `other three-dimensional crimp-like configurations between the Welds. In addition, the filaments are somewhat softened and make additional bonds with adjacent filaments as the expansion creates new points of contact. The movement of the filaments increases the interlocking of filaments so that the final structure is stronger, in addition to being less dense as a result of the threedimensional bulking. At the same time there is an improvement in the hand of the non-woven, i.e. it becomes softer.

In the event that the filamentary material of the nonwoven is initially more or less oriented and the nonwoven accordingly much stronger in one direction than another, the steaming decreases the orientation and reduces the differential strength.

In spite of their increased strength and `abrasion resistance, the products may be completely free of extraneous binders and/ or plasticizers.

The steaming treatment can be effected with the nonwoven starting material in sheet form either flat or wound in a roll loosely about a shaft. Alternatively the nonwoven may be in a form approximating that required for an end use, e.g. it may -be wound about a perforated cylindrical core in a f-orm suitable for use as a cylindrical oil filter cartridge. The non-woven may be incorporated as an interlining or filling material between layers of fabric or the like and the composite article may be subjected to steaming. In general, the product will be useful wherever non-wovens have heretofore found application.

The invention will be more fully described with reference .to the accompanying drawing, wherein:

FIG. 1 is .an elevation of an apparatus for forming a composite nonawoven, with t-he front cover shown in section;

FIG. 2 is an elevation of a steaming apparatus with the front cover shown in section;

FIG. 3 is a plan View of a non-woven sheet prior to steaming; and

FIG. 4 is a plan vieiw of the sheet of FIG. 5 after steaming.

Referring now more particularly to the drawing, in FIG. 1 there is shown a closed cabinet 11 housing an endless highly porous member such as a wire screen 12 trained about shafts `13, 14, at least oneof which is rotate-d, at relatively lo-w speed, so that the top of screen 12 moves to the right. `Hot air is admitted lto the cabinet 11 through a line 15 and leaves with solvent vapors through an exhaust 16.

A first solution of Iilament forming material, e.g. conventional cellulose acetate in acetone, is extruded as a plurality of filaments through a spinnerette 17; a second solution 4of filament forming material, e.g. cellulose -triacetate in methylene chloride, is extruded through spinnerette 118. Blasts of .air are ydirected at the two sets of filaments through nozzles 19 and 20, causing Ithe filaments to swirl about and to contact one another while still wet with solvent and in mutually adhesive condition. The iilament-s fuse or form welds at their contact points and deposit on screen 12 as a randomly directed fleece 21 which leaves cabinet 11 through an opening defined by a pair of rolls, 22, 23 which prevent excess leakage of solvent vapors from the cabinet. The fleece 21 is taken -up loosely on a roll 24 simultaneously with a separating web 25 such as paper unrolled from a supply package 26. W-hen the roll 24 reaches a predetermined size the fleece 21 .and web 25 supplying the roll 24 are cut, the roll 24 is removed and a new roll is started.

The roll 24 of predetermined size is placed in an en* closure 26 (FIG. 2) and steam is admitted through line 27 with all other lines' closed. After a predetermined time line `27 is closed to terminate steaming, line 28 is lopened and relatively cool air is forced in through line 29 to Ipurge the steam and to cool the roll 24. The roll 24 is then removed and can be used in conventional manner, stripping the paper separator 25 as the roll is unwound.

In FIG. 3 there Iis shown la non-'woven sheet material 30 composed of substantially continuous filaments 31 of relatively high denier. The sheet is very iia-t and has a high gloss and stili hand, the -laments having a plastic rather than a textile appearance. After steaming, the product has the appearance illustrated in FIG. 4. The sheet is about twice as thick, the luster is reduced considerably and, while still somewhat stiff, the feel is similar .to that of a starched natural fiber web rather than a plastic. In addition, the individual filaments are characterized by numerous crimps extending in three dimensions which increase .the covering power of the article.

With initially more dense non-wovens the same differences will result, but the individual filaments are not as readily identifiable, except on closer observation.

The following examples lare given to illustrate the invention further.

CTI

4 Example I Using the apparatus shown in FIG. 1, except that spinnerette 18 is inoperative, a heated dope of cellulose acetate in acetone is extruded through spinnerette 17 provided -wit-h 6 circular lorifices each 126 microns in diameter. The linear speed of extrusion through the orices is 3750 meters per minute, and the speed of screen `12 is 75 meters per minute. The denier of the filaments of the non-fwoven ranges from about 2 to 7 and i-ts weight is 2 ounces per square yard. This material is illustrated in FIG. 3 of the drawing. After au-toclaving for 8 minutes with steam at 121 C. and 15 p.s.i.g. the non-woven shrinks in width from an initial value of 4.5 inches down to 4.3 inches. The sheet weighs about 2.1 ounces per square yard and its thickness has increased from about 0.02 to 0.06 inch. The product is illustrated in FIG. 4.

It is -to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention what we desire to secure by Letters Patent is:

1. A bulky non-woven filter article comprising a layer of substantially continuous substantially randomly directed cellulose ace-tate filaments fused to one another at spaced points, said fila-ments ranging in denier from about l to 20 and being crimped in three dimensions between fusion points as a result of having :been contacted Iwith steam.

2,. A filter cartridge comprising a perforated core containing a roll of a bulky nonwoven sheet material cornprising substantially continuous substantially randomly directed cellulose acetate filaments fused -to one another at spaced points, said filaments ranging in -denier from about 1 to 20 and being crimped in three dimensions between fusion points as a result of having been contacted with steam.

References Cited by the Examiner UNITED STATES PATENTS 1,794,227 12/1931 Gearow 131-10 2,357,392 `9/1944 Francis.

2,517,694 8/1950 Merion et al 28-82 2,647,297 8/1953 Batista 161-150 2,715,763 8/1955 Marley 28-82 2,763,267 9/1956 Muller 131--208 2,839,065 -6/ 1958 Milton 131--10 2,916,038 12/1959 Wade 131-10 2,968,857 1/1961 'Swerdlol et al 13b-208 3,023,075 2/1962 Larman et al 131-208 3,025,130 3/1962 White 131-208 3,039,908 6/1962 Parmele 131-208 3,062,611 11/19-62 Keen 18-54 3,079,930 3/1963 Cobb et al 131-208 3,081,145 3/1963 Ernst evt al 18-54 3,093,142 6/1963 Swerdlof 131-10 SAMUEL KOREN, Primary Examiner.

MORRIS LIEBMAN, ABRAHAM G. STONE,

Examiners.

C. B. HAMBURG, M. D. REIN, Assistant Examiners. 

2. A FILTER CARTRIDGE COMPRISING A PERFORATED CORE CONTAINING A ROLL OF A BULKY NON-WOVEN SHEET MATERIAL COMPRISING SUBSTANTIALLY CONTINUOUS SUBSTANTIALLY RANDOMLY KDIRECTED CELLULOSE ACETATE FILAMENTS FUSED TO ONE ANOTHER AT SPACED POINTS, SAID FILAMENTS RANGING IN DENIER FROM ABOUT 1 TO 20 AND BEING CRIMPED IN THREE DIMENSIONS BETWEEN FUSION POINTS AS A RESULT OF HAVING BEEN CONTACTED WITH STEAM. 